The Ukrainian government launched a military operation in its southeast Donbas region in 2014, after the pro-Russia residents refused to recognise the pro-West Ukrainian authorities and sought independence.

Kiev and the insurgents reached a peace agreement brokered by Russia, France and Germany in Minsk, capital of Belarus, in 2014, with a more detailed renewal of the agreement, or Minsk II agreement, signed in February 2015.

Urging the Russian government to cease its "aggression" in Ukraine, Nauert said the US sanctions will "remain in place" until Russia fully implements its commitments under the Minsk agreements.

She added that the West's separate Crimea-related sanctions will also remain in place until Russia "returns the peninsula to Ukraine."

Crimea, formerly part of Ukraine, was absorbed into Russia in March 2014 following a local referendum, which was rejected by Ukraine and its allies.